Research On Current Data Processing Method Of High Frequency Surface Wave Radar

The current data mainly comes from the measured data obtained by observation equipment and numerical simulation data.Traditional fixed current observation equipment can't cover a large area,which utilize one or more points detection data to represent the regional current distribution.In addition,it costs more manpower,material,financial resources and time.The ocean numerical model can simulate current data in real time efficiently.But the current calculation accuracy is low,and it is difficult to simulate the real current state and has a certain limitation in application.The high frequency ground wave radar has the characteristics of large detection range and all-weather working,which can be used to analyze current characteristics comprehensively.It is of great significance to study and analyze the current data of HF ground wave radar.In this paper,a series of study of ocean current data is developed based on the current data obtained by the miniature circular array muti-frequency HF ground wave radar,which is developed by the radio remote sensing laboratory.Firstly,we used harmonic analysis of tidal current to analyze the characteristics of the tidal current in the East China Sea near Zhoushan island.The result shows that the main tidal current characteristics in the analysis area are regular semidiurnal tides,and some of the coastal areas are irregular semidiurnal tides.The magnitude of M2 is the strongest.Its maximum flow velocity is between 26-40cm/s and the direction is from northwest to southeast.The rotation direction of M2 is clockwise.The tidal current distribution is affected by the terrain factors.The nearshore area is affected by the shallow water tide,and it has a large shallow water tidal velocity.By carrying out harmonic analysis of tidal current,we built the foundations for the research of current data reconstruction and assimilation in the following article.Then,because HF radar is often effected by environment factors and has self detection defect,the current data detected by HF radar has missing data.To solve this problem,we proposed Kriging method and DCT-PLS methods to reconstruct the missing data.We used measured data to implement two kinds of experiments to get the reconstruction results,including random missing data experiment and large area missing data experiment.The error between the reconstructed data and the original data is analyzed by using the statistical evaluation criteria,the correlation coefficient evaluation criteria and the results of harmonic analysis.Through the analysis we concluded that with the increase of the original data acquisition rate,the quality of reconstruction data is better.In high original data acquisition rate,Kriging algorithm based on the spatial data to reconstruct data has better performance.While in low original data acquisition rate,DCT-PLS algorithm based on spatio-temporal information to reconstruction performs well,and it also smooth the result and has good robustness.For the reconstruction of large area missing current data,the two algorithm can reconstruct the missing data successfully.The DCT-PLS algorithm has smaller error and better performance than the Kriging algorithm in the missing area,and it also smooth the data not in missing area.In the two kinds of experiments,the two algorithm can restore the distribution characteristics of the original data,and the DCT-PLS algorithm has smaller error.Comparing the consuming computation time of the two methods,with the increase of the original data acquisition rate,the time consuming of Kriging algorithm increases linearly,while the DCT-PLS algorithm is more stable.Finally,we used the POM model to simulate the current distribution.Then,the HF ground wave radar data are assimilated into the POM model by SCM to obtain the assimilation current data.To analyze the result we found that the error between the original data and the data after assimilation is less than the error between original data and the model data.After assimilation,the characteristics of tidal distribution is more close to the original data.Current data assimilation improves the model simulation results of current.